Clones having optimal antibody expression characteristics are typically selected during the development of production cell lines for the generation of therapeutic monoclonal antibodies. Clones having optimal expression characteristics are expanded and frozen for future antibody production cultures. Despite the exceedingly controlled environment in which a production cell line is used, as the cells propagate and express antibody, the cell line accumulates cells that are “low expressors.” As a result, the production levels of the culture as a whole decreases, and the cost of antibody production increases.
Accordingly, it is highly desirable to have a system whereby one can easily identify and select high expressors within a recombinant cell culture for future production runs. We have developed an immunoglobulin expression vector that allows simultaneous expression of membrane-bound and soluble forms of an immunoglobulin.